Fiat 1996 Brava Service Manual page 575

Auxiliary units
Climate control
Bravo-Brava
98 range
50.
"MAX-DEF" Function
With the distribution knob turned completely
in a clockwise direction the "MAX DEF"
rapid demisting function is activated by a
special microswitch. This function involves:
- maximum air flow rate
- mixture with maximum heat available
- recirculation switched off, whatever posi­
tion the button (5) is in
- compressor enabled, whatever position the
button (4) is'in
- signal requesting engagement of heated
rear windscreen : this engagement is man­
aged by the integrated services control unit
(see Group 55)
Compressor engagement
When the button shown in the diagram is
pressed this enables the OPERATION OF
THE COMPRESSOR (air refrigeration cir­
cuit); if the button is released, the operation
ceases.
The effective engagement of the compressor,
however, depends on the following condi­
tions:
- outside temperature below 5°C: (switches
off below 4°C and switches on again above
6°C)
- temperature detected by the frost sensor:
(switches off below 3.5°C and switches on
again above 5°C)
P4A04CH02
It should be rememebered that the compressor can also be switched off through the intervention of the
four stage pressure switch or the engine control unit. This logic dependson the different engine jnan-
agement control units, as detailed below:
CONNECTION WITH THE ENGINE CONTROL UNIT
The electronic control unit for the climate control system sends a command signal to the engine control
unit giving the go ahead required for engaging the compressor.
There are two different types of connection according tothe type of engine control unit
A: 1242 - 1581 - 1998 - 1910 JTD engines
B: 1910 TD 75 engine (Soft)
NOTE For the 1747 version, refer to the details in the previous edition (print no.506.670/01).
NOTE Forthe 1910 TD 75 version, which does not have an engine control unit, the go ahead for oper­
ating the compressor is given by a special thermal switch and by the EGR control unit, as well as
the four stage pressure switch.
4 Print no. 506.670/16